#include "params.h"
#include <math.h>


#ifndef _BACKGROUND_H_
#define _BACKGROUND_H_

#define idx_a	0
#define idx_z	1
#define idx_H	2


typedef struct _background{

	int size;	//
	double *datablock;
} background;


//  return H(a) as a function of scale factor a in unit of km/s/Mpc
double H_a( double a, void *p );

//  return H(z) as a function of redshift z in unit of km/s/Mpc
double H_z( double z, void *p );

#endif	// _BACKGROUND_H_
